 /*******************************************************************************
  * Copyright (c) 2004, 2007 IBM Corporation and others.
  * All rights reserved. This program and the accompanying materials
  * are made available under the terms of the Eclipse Public License v1.0
  * which accompanies this distribution, and is available at
  * http://www.eclipse.org/legal/epl-v10.html
  *
  * Contributors:
  * IBM Corporation - initial API and implementation
  *******************************************************************************/
 package org.eclipse.ui.actions;

 import org.eclipse.jface.action.ContributionItem;
 import org.eclipse.jface.action.IContributionItem;
 import org.eclipse.jface.action.IContributionManager;
 import org.eclipse.jface.action.IMenuListener;
 import org.eclipse.jface.action.IMenuManager;
 import org.eclipse.swt.SWT;
 import org.eclipse.swt.widgets.Menu;
 import org.eclipse.swt.widgets.MenuItem;

 /**
  * A compound contribution is a contribution item consisting of a
  * dynamic list of contribution items.
  *
  * @since 3.1
  */
 public abstract class CompoundContributionItem extends ContributionItem {

     private boolean dirty = true;

     private IMenuListener menuListener = new IMenuListener() {
         public void menuAboutToShow(IMenuManager manager) {
             manager.markDirty();
             dirty = true;
         }
     };
     
     private IContributionItem[] oldItems;
     
     /**
      * Creates a compound contribution item with a <code>null</code> id.
      */
     protected CompoundContributionItem() {
         super();
     }

     /**
      * Creates a compound contribution item with the given (optional) id.
      *
      * @param id the contribution item identifier, or <code>null</code>
      */
     protected CompoundContributionItem(String id) {
         super(id);
     }
     
     /* (non-Javadoc)
      * @see org.eclipse.jface.action.ContributionItem#fill(org.eclipse.swt.widgets.Menu, int)
      */
     public void fill(Menu menu, int index) {
         if (index == -1) {
             index = menu.getItemCount();
         }
         if (!dirty && menu.getParentItem() != null) {
             // insert a dummy item so that the parent item is not disabled
 new MenuItem(menu, SWT.NONE, index);
             return;
         }
         
         IContributionItem[] items = getContributionItemsToFill();
         for (int i = 0; i < items.length; i++) {
             IContributionItem item = items[i];
             int oldItemCount = menu.getItemCount();
             if (item.isVisible()) {
                 item.fill(menu, index);
             }
             int newItemCount = menu.getItemCount();
             int numAdded = newItemCount - oldItemCount;
             index += numAdded;
         }
         dirty = false;
     }
     
     /**
      * Return a list of contributions items that will replace this item in the
      * parent manager. The list must contain new contribution items every call
      * since the old ones will be disposed.
      *
      * @return an array list of items to display. Must not be <code>null</code>.
      */
     protected abstract IContributionItem[] getContributionItems();
     
     private IContributionItem[] getContributionItemsToFill() {
         if (oldItems != null) {
             for (int i = 0; i < oldItems.length; i++) {
                 IContributionItem oldItem = oldItems[i];
                 oldItem.dispose();
             }
             oldItems = null;
         }
         oldItems = getContributionItems();
         return oldItems;
     }
     
     /* (non-Javadoc)
      * @see org.eclipse.jface.action.ContributionItem#isDirty()
      */
     public boolean isDirty() {
         return dirty;
     }
     
     /* (non-Javadoc)
      * @see org.eclipse.jface.action.ContributionItem#isDynamic()
      */
     public boolean isDynamic() {
         return true;
     }
     
     
     /* (non-Javadoc)
      * @see org.eclipse.jface.action.ContributionItem#setParent(org.eclipse.jface.action.IContributionManager)
      */
     public void setParent(IContributionManager parent) {
         if (getParent() instanceof IMenuManager) {
             IMenuManager menuMgr = (IMenuManager) getParent();
             menuMgr.removeMenuListener(menuListener);
         }
         if (parent instanceof IMenuManager) {
             IMenuManager menuMgr = (IMenuManager) parent;
             menuMgr.addMenuListener(menuListener);
         }
         super.setParent(parent);
     }
 }

